Vacuum tube



Jan. 10, 1928. 1,655,820

. G. H. PERRYMAN VACUUM TUBE Filed May 22, 1926 av 20 Z 20 b Z7 I 7 104 lNVENTOR Patented Jan. 10, 1928.

UNITED STATES PATENT OFFICE.

aGrIiOJztGIEl H. PERRYMAN, F YORK, N. Y., ASSIGNOR T0 PERRYMAN ELECTRIC GOMPANY, INC., 0] NEW YORK, N. Y., A CORPORATION OF NEW YORK.

VACUUM. TUBE.

Application vfiled May 22, 1926. Serial No. 110,862.

This invention relates to a vacuum tube or thermionic device and has for its object to provide such a device with a high voltage lead-in wire so arranged that the possibility of short circuit between said wire and the other lead-in wires is prevented. It is well known that in tubes of the type known as power amplifier tubes the lead-in wire supplying voltage to the anode or plate can 1 ries a high voltage amounting in some 1nstances to as much as 500 volts. It is therefore desirable that this lead be spaced asfar as possible from the filament lead-in wlres which carry a low voltage. It is also desirable that where possible, the greatest amount of insulating material or glass be placed between the high voltage lead-in wire and the other lead-in wires.

The primary object therefore of my in go Vention is to provide a high vvoltage leadin wire so located that the desirable results mentioned above will be attained and said lead-in wire may be properly positioned during the ordinary manufacture of the tube without entailing extra operations or labor. Referring to the accompanying drawlngs Figure 1 is a sectional view of my 1mproved vacuum tube with parts being broken away and the tube base omitted to disclose construction; and

Figure 2 is a sectional view of the lower part of the tube in the process of being man-' ufactured and showing the envelope or casing being fused to the flare of the stem.

Throughout the various views of the drawings, similar reference characters designate similar parts.

' In the embodiment of my invention disclosed in the accompanying drawing, 1 in dicates the outer envelope or glass casing of the tube which is, in the process of manufacture fused to the lower end or flare 2 of the glass stem 3. Passing through the stem 3 are thefilament lead-in wires 4 and 5 which 5 extend upward and support the filament 6. The filament is resiliently supported also by means of the s rings 7 which rest upon a cross-brace. 8 and engage with the filament.

so At 10 is the lead-in to the grid which is shown .at 11. The plate or anode is shown at 12 and this is sup orted upon rods 13 and 14 which are secured at theirlower ends to a band or strap 15 which surrounds the stem3.

"ward and it positions itself between the avehooked ends 9 which.

At 16 is the lead-in wire which supplies the plate voltage and said lead-in wire comprises a thick or rigid upper part 17 which isfused to the rod 14. Extending from the part 17 is a thinner or lighter wire 18 which runs substantially parallel to the stem 3 and passes out of the tube shell at the juncture 19 of the outer envelope and stem flare 2. It will be seen fromthe foregoing that the position of the lead-in wire 16 is such that it is spaced at a considerable distance away from the other lead-in wires 4, 5 and 10 and as it is completely outside of the glass stem 3, while the other wires are contained within the same, an amount of insulating material or glass is interposed between said wire 16 and the other lead-in wires 4, 5 and 10. Y

The method of manufacturing the tube, a far as the sealing-in operation of the wire 16 is concerned, is diagrammatically illustrated in Figure 2. The stem with the attached tube parts is held on a suitable support (not shown) and preferably in a vertical position. The glass envelope 1 is placed overthe same and heat is applied to the lower end of the envelope 1 as is indicated at 20 in Figure 2.

The lead-in wire normally extends downedge 21 of the flare 2 on the stem and the lower part 23 of the envelope so that when Y the heat 20 is applied and the stem 3 and en .velope 1 are fused together, the wire 16 is effectively sealed in at the juncture of the flare 2 and envelope 1 as will be clearly seen in Figure 1. Since the joining together of" the'st-em 3 and outer enilelope 1 of the tube is a normal operation in tube manufacture, it will be seen that no extra steps, with consequent extra expense are required. At the same time, the lead-in wire is rigidly held and is'elfectively spaced from the other leadin wires, which in tubes of the character herein described, is very desirable? It will be seen in Figure 2 that the envelopexis, before it is seaL-d to the stem 3,'of greater length than is actually required, so that the lower skirt portion part 23 of said envolope is dependent below the lower termination on the stem 3. The act of sealing together the flare 2 on the stem 3 and the lower end of the envelope-unites these with the, lead-in wire 18 between them and simultaneously serves to remove the excess glass on the end of the envelope, said excess glass dropping off, leaving the tube in the eondi;

'tion disclosed in Figure l. I

Having described my invention, what I 5 claim is:

w The process of making a vacuum tube c0nsisting in surrounding a tube stem with an envelope so that a lower dependent skirt portion on said envelope will be caused to 10 project a considerable distance below the lower termination of the stem, in placing a high voltage lead-in Wire extending from the tube anode between theedges ofthe stem and the dependent skirt portion, in fusing together" the edges of the stem and the dependent skirt. on the envelope so that the lead-1n wire is sealed in said joint and in simultaneously removing excess glass from the e. H. PERRYMANQ 

